Bituminous structural material.



H. R. WARDELL. BITUMINOUS STRUCTURAL MATERIAL.

APPLICATION FILED JULY 24, 1908.

Patented May 17, 1910.

W'ii-NE-SE: u

HENRY noBBiNs wannnrln, j or PHILADELPHIA, PENNSYLVANIA.

1 n'rrommous srnuo runa'n jiA'rERIAL.

Specification bf Letters mm.

- I Application filed July 24, 1908. Serial No. 445,083.

provements in Bituminous Structural Materials, of which the following is a specification, reference being had to the accompanying drawings. Y

My improvements relate to a structural material in the form of a composite sheet composed of bituminous cements combined with textile or felted fabrics, and it is the object of my invention to roduce such a composite sheet having su cient strength and rigidity to be in itself a self-supporting structural material, as for example, fora wall -or a roof of a building. 1

To this end-my material is composed of several layers, of which the external or surface ones are essentially protective layers,

while the internal layer is a stiifening one, having both strength and rigidity so that, especially when corrugated, it may be-used by itself to form the roof or the wall of a building. I

Many composite roofing sheets or other forms of sheathing sheets have been made by the combination of felted and textile materials with bituminous cements, but it has always heretofore been supposed that, such bituminous cements were too soft, especially when ex osed to higher sun temperatures, to admit 0? their attaining a permanent consistency which would make the sheet rigid enough without brittleness to be useful as a. structural material in itself. Consequently, all these previous bituminous composite sheets have been applied to an already existing surface, usually of boards, and have served only as sheathing therefor,

but the sheet which I have invented possesses such strength and rigidity without brittleness that it may be corrugatedand will retain its corrugation even underthe extreme heat of the summer sun. In contradistinction to these sheathing sheets my invention is capable of being applied just as metallic structural, sheets are now applied for the purpose of makin the walls or roof of other parts of a buildmg, without other sustaining means than the ordinary wooden or metal framework used in such-cases.

My invention depends u on the principle, discovered by myself, that: y employin external protective layers, an internal inuminous sheet may be made andmaintained with such consistency, rigidity and strength as to successfully hold its shape against the ordinary distortin strains to which such structural materia s are subject, notwithstanding the deteriorating influences of the atmosphere, weather and sun. It is obvious that 'it enables buildings to be constructed more cheaply, dispensingentirely with the material ordinarily used for the walls or roofs, since possessing as it does waterproof, weather-proof, and fire resisting qualities, the sheet serves in itself to form a lasting wall or roof without the use of any other material than the supporting framework. Being unafiected by moisture or the corrosive gases which attack iron, it is a more durable substitute for corrugated iron sheets as a structural material. I

.In United States Letters Patent No. 851,331, granted to me under date of April 23rd, 1907, for a compound roofing sheet, .I have described a composite bituminous sheet having certain of the characteristics" of my present invention, and like it in some of its patented by me did not possess the strength and rigidity requisite to allow the sheet-t0- quently, such sheet required a supporting surface for its application. It was, therefore, quite a different thing from my .pres-v ent invention, but in sofar as certain of the parts of my :present invention correspond to similar parts in the sheet previously patthe description of suchparts Without here repeating 1t.

In the accompanyin represents aportion o a a composite cox-ru gated sheet embodying my invention. -Fig. II, illustrates mytmvention as applied to a corrugated sheet of different construction.

Primarily my present structural material is a composite sheet built up of two kinds of layers But. each of these layers may itself be composite so that the entire sheet may contain a large number of layers, but for functional distinction it is convenient to sub-divide all the layers into two, to wit: a rigidstrengthening and sustaining layer, and an external protective layer;

- Referring to Fig. I, of he drawing, it will be observed that the material is shown with its layers successively cut away so as to drawing, Figure 'I, i

OFFICE.

Patented May'1'7, 1910. I

that such a sheet is of very great value in a parts. But the roofing sheet thus previously.

I be corrugated or to hold its shape. I Conseented, I may refer to my previous patent for disclose the structure as it is built up by the superimposition of successive layers. Of these, 1 is an external protective layer, 2, is the central strengthenin layer, and 3, another protective layer. The external layers 1, and 3, consist of a felted fabric or other similar basis, such as roofing paper, or roofing felt, or wool felt, thoroughly saturated by an asphaltic or bituminous compound as described in my previous patent, to which reference is made for description of the protective layers. Upon the surfaces of this saturated protective layer additional thin layers of bituminous material may be applied, these being so thin as not to be capable of disclosure in the drawing. It is upon the central layer 2, that my present invention depends. This is preferably formed of a hard pure native bitumen, such as grahamite, wurtzilite, gilsonitc or the like. This is properly fluxed until it is of such consistency at 7 7 Fahrenheit, that when tested for five seconds with a No. 2 cambric needle under a hundred gram weight, it will be penetrated to a depth of 0.10 mm. It is obvious that the consistency of this cement may be slightly varied, depending upon the viscosity of the native bitumen employed, so long as the main object is attained, which is to produce a piece of structural material which will retain its shape and corrugation under maximum sun tern eratures. To some extent the climatic con itions under which the structure is to be used will influence the consistency of this cement, for obviously a harder material must be employed in the tropics than in colder regions. To increase the strength of this layer I prefer to embed therein a layer of coarse burlap or wire mesh 5. The wire mesh to be employed may vary from say a twelve wire mesh to a three-eighths mesh wire. I preferthe wire mesh to the burlap, since it has greater strength and some rigidity, but for cheap forms of construction the burlap may be employed. The thickness of this central layer may vary according to the strength required. I have found that a'thickness of about 1/16 of an inch is suflicient for ordinary'purposes. To each side of the central layer 2, thus formed, protective layers 1, and 3, are applied, the three being united in the course of their manufacture to form one substantially integral structure. It is obvious that if desired for increased strength the central layer may be reduplicated, or increased in size.

In Fig. II, I have shown an embodiment of my invention in which the strength and rigidity of the material is increased, by additional layers of heavy Manila paper 4, 4:, interposed on either side of the central layer between it and the external protective layers, and these layers of Manila paper may be repeated to whatever extent is found desirable. After the composite sheet comprising my invention has been thus built up, it is, while still soft from the heat of manufacture, corrugated by the use of ordinary corrugating rolls, or other suitable means and by reason of the hard consistency of the central layer, the corrugations thus imparted are retained, so that the entire sheet has structural or self-sustaining properties similar to those of the ordinary corrugated metallic roofing sheet. When tested at ordinary temperatures the corrugated sheet' may be walked upon by a heavy person without appreciable distortion of the corrugations. Accordingly the sheets thus prepared are employed as has been explained to form the wall or the roof or other structural part of the building without other sustaining surfaces. It is thus distinguished from roofing sheets, not only in its selfsustaining capacity, but by its method of application. Roofing sheets are nailed to a wooden backing and the joints are rendered tight and waterproof by a bituminous varnish or liquid cement. My structural sheets may be used in the same manner as corrugated iron attached' only to a frame and with overlapping joints without cementin It will be'understood that it would be d' cult if not impossible, to secure to this central sheet the requisite strength .and self- .sustaining qualities, and at the same time to maintain them under atmospheric deteriorating influences, were it not for the external protecting sheet which shields the strengthening sheet from such influences, so

that the bituminous material although hard, may possess and maintain suflicient life, (due in the main to the manner in which the bitumen has been fluxed), to prevent its becoming brittle and breakable under bination with one or more external protective bituminous sheets of a softer character.

In testimony whereof, I have hereunto signed my name, at Philadelphia, Pennsylvania, this twenty-third day of July 1908. HENRY ROBBINS WARDELL.

Witnesses:

- JAMES I-LBELL,

E. L. FULLERTON.

the influences of sun and air and weather. I 

